Cooperative Scheme for Backscatter-Aided Passive Relay Communications in Wireless-Powered D2D Networks

In wireless-powered device-to-device (D2D) networks with backscatter-aided passive relays, the cooperation among D2D pairs is of special necessity. With the cooperation among D2D pairs, the devices can act as passive relays to enhance the signal reception, and share their active transmission time to improve the resource utilization. Therefore, how the D2D pairs form coalitions and how to reallocate the active transmission time to the D2D pairs after forming coalitions should be studied. In this article, we develop a hierarchical cooperative game framework for the network to investigate how the D2D pairs cooperate with each other. Specifically, in the upper layer of the game, we employ the coalition game to formulate how the D2D pairs form coalitions and analyze the stability of the coalition structure and the complexity of the proposed strategy. In the lower layer of the game, we employ the bargaining game to investigate how the D2D pairs share the active transmission time, and analytically evaluate the complexity of deriving the Nash bargaining solution. Simulation results demonstrate the effectiveness of our proposed scheme. The results also show that the computational complexity of our proposed scheme is only a small fraction of that of the exclusive search-based scheme. Nevertheless, compared with the exclusive search-based scheme, the total effective amount of the transmitted data in the proposed cooperative scheme reduces no more than 2%, which is very minor.